Microfluidic Assay for Neutrophil Chemotaxis Towards Chemoattractant Gradients (173.13)

Abstract

Abstract Chemoattractants represent an essential group of molecular guidance signals that regulate the transit of leukocytes out of the mainstream of blood and into tissues at sites of inflammation. In this project, we developed a microfluidic device that is simple to operate and allows for precise and robust measurements of neutrophil chemotaxis speed and directionality towards precisely defined chemoattractant gradients at single-cell resolution. These devices consist of non-planar, enclosed microenvironments of increasing complexity, from straight channels, to channels with posts and simple mazes. The cross-section of the channels (3 × 6 μm) is smaller than the human neutrophils, so that cells are mechanically confined and allowed to move only along the axis of the channels toward a gradient of chemoattractactant. This assay is currently being applied in a clinical setting to characterize the immune function in burn patients during treatment. Comparing samples from healthy donors to burn patients revealed impaired directional migration speed starting as early as 24 hours after burn injury, reaching a minimum at 72 hours, correlated to the size of the burn injury and potentially serving as an early indicator for concurrent infections. Further characterization of neutrophil chemotaxis using this new assay may have important diagnostic implications not only for burn patients, but also for patients afflicted by other diseases that compromise neutrophil functions.